Esters of perfluoroalkyl terminated alkylene thioalkanoic acids and their derivatives have been described in the prior art (U.S. Pat. No. 3,759,981). These surfactants suffer from a marked unstability of the ester function towards hydrolysis and consequently are of little practical use.
The amides of this invention, however, are very stable to hydrolysis and therefore find many uses as surfactants and wetting agents.
Perfluoroalkylthioamide amine and ammonium compounds of this invention are useful as surface active agents or as surface treating and coating agents. The novel compounds are obtained by the addition of a perfluoroalkylthiol to an amide of an .alpha., .beta.-unsaturated acid. The cationic and amphoteric salts of these compounds are also described.
The compounds of this invention can be represented by the formulae ##STR2## WHERE R.sub.f is straight or branched chain perfluoroalkyl of 1 to 18 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 atoms;
R.sub.1 is branched or straight chain alkylene of 1 to 12 carbon atoms; alkylenethioalkylene of 2 to 12 carbon atoms; alkyleneoxyalkylene of 2 to 12 carbon atoms; or alkyleneiminoalkylene of 2 to 12 carbon atoms where the nitrogen atom contains as a third substituent hydrogen or alkyl of 1 to 6 carbon atoms; PA1 R.sub.2 is hydrogen or straight or branched chain alkyl of 1 to 6 carbon atoms; PA1 R.sub.3 and R.sub.4 each is independently straight or branched chain alkyl of 1 to 22 carbon atoms; or R.sub.3 and R.sub.4, together with the nitrogen to which they are bonded, form a heterocyclic ring: PA1 R.sub.5 is hydrogen or straight or branched chain alkyl of 1 to 6 carbon atoms. PA1 R.sub.6 is hydrogen; oxide; or straight or branched chain alkyl of 1 to 22 carbon atoms that may be substituted with 1 or 2 hydroxyl groups, a free carboxylic acid group, or an anionic function selected from sulfonate, sulfate, or carboxylate; PA1 E is a straight or branched chain alkylene of 1 to 12 carbon atoms; or alkylene (polyoxyalkylene) of formula EQU C.sub.m H.sub.2m (OC.sub.k H.sub.2k).sub.r PA1 m is an integer of 1 to 12; PA1 k is an integer of 2 to 6; PA1 r is an integer of 1 to 40; PA1 y is 1 or 2, depending on the valence of X; and PA1 z is 0 or 1, with the proviso that when z is 0, y is 1 and R.sub.6 must be oxygen or an anionic function; if z is 1, R.sub.6 may not be oxygen. PA1 R.sub.f is straight or branched chain perfluoroalkyl of 6 to 12 carbon atoms or said perfluoroalkyl substituted by perfluoroalkoxy of 2 to 6 carbon atoms; PA1 R.sub.1 is branched or straight chain alkylene of 2 to 8 carbon atoms; alkylenethioalkylene of 2 to 8 carbon atoms: alkyleneoxyalkylene of 2 to 8 carbon atoms; or alkyleneiminoalkylene of 2 to 8 carbon atoms where the nitrogen atom contains hydrogen or methyl as a third substituent; PA1 R.sub.2 is hydrogen or methyl; PA1 R.sub.3 and R.sub.4 each is independently straight chain alkyl of 1 to 12 carbon atoms; or R.sub.3 and R.sub.4, together with the nitrogen to which they are bonded form a heterocyclic ring; PA1 R.sub.5 is hydrogen; PA1 R.sub.6 is hydrogen; oxide; or straight chain alkyl of 1 to 3 carbon atoms that may also contain 1 hydroxyl group, a free carboxylic acid group, or an anionic function selected from sulfonate, sulfate, of carboxylate; PA1 E is a straight chain alkylene of 2 or 3 carbon atoms; or alkylene (polyoxyalkylene) of formula EQU C.sub.m H.sub.2m (OC.sub.k H.sub.2k).sub.r PA1 m is an integer from 1 to 4 PA1 k is an integer from 2 to 4 PA1 r is an integer from 1 to 20, PA1 X is an anion selected from the group consisting of Br, Cl, I, acetate, phosphate, sulfate, methosulfate or ethosulfate; PA1 y is an integer equal to the valence of X; PA1 z is 0 or 1, with the proviso that when z is zero, y is 1, and R.sub.6 must be oxygen or an anionic function; when z is 1, R.sub.6 may not be oxygen. PA1 R.sub.f is perfluoroalkyl of 6 to 12 carbon atoms or perfluoroalkoxyperfluoroalkyl of 4 to 12 carbon atoms, and especially where R.sub.f if (CF.sub.3).sub.2 CFO(CH.sub.2 CF.sub.2 --.sub.y where y is an integer from 1 to 6.
where
or E together with the two nitrogen atoms and R.sub.3 forms a piperazine ring having the structure ##STR3## X is an anion selected from the group consisting of Br, Cl, I, acetate, phosphate, sulfate, methosulfate or ethosulfate;
Preferred compounds are those where
where
or E together with the two nitrogen atoms and R.sub.3 forms a piperazine ring;
The novel R.sub.f -surfactants described herein can be obtained either:
a. directly by the base-catalyzed addition of a perfluoroalkylthiol of formula EQU R.sub.f R.sub.1 SH
to an .alpha.,.beta.-unsaturated amide of formula EQU CH.sub.2 .dbd.CR.sub.2 CONR.sub.5 ENR.sub.3 R.sub.4
where R.sub.f, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and E are defined above, or
b. indirectly by the further reaction of the above products with such quaternizing agents as alkyl halides, dialkyl sulfates and the like to yield cationic surfactants or with inorganic acids or organic acids to form salts, or by reaction with such alkylation reagents as chloroacetic acid, sodium chloroacetate, propane sultone, propiolactone and the like, to yield amphoteric surfactants. Amine oxide derivatives wherein R.sub.6 is oxygen are prepared by treatment with hydrogen peroxide at about 0.degree. to 50.degree. C.
One group of preferred compounds has the formula EQU R.sub.f CH.sub.2 CH.sub.2 SCH.sub.2 CH(CH.sub.3)CONH(CH.sub.2).sub.3 N(CH.sub.3).sub.2
and the corresponding ammonium derivatives EQU [(R.sub.f CH.sub.2 CH.sub.2 SCH.sub.2 CH(CH.sub.3)CONH(CH.sub.2).sub.3 N(.sup.+ CH.sub.3).sub.2 C.sub.2 H.sub.5)]C.sub.2 H.sub.5 SO.sub.4.sup.-
and EQU R.sub.f CH.sub.2 CH.sub.2 SCH.sub.2 CH(CH.sub.3)CONH(CH.sub.2).sub.3 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 CO.sub.2.sup.-
where
In one embodiment, the .alpha.,.beta.-unsaturated amide has the formula EQU CH.sub.2 .dbd.CR.sub.2 CONHENR.sub.3 R.sub.4
where E is a straight chain alkylene of 2 to 3 carbon atoms, and R.sub.3 and R.sub.4 are each independently straight chain alkyl of 1 to 3 carbon atoms; or R.sub.3 and R.sub.4 together with nitrogen forms a morpholinium group. In a preferred embodiment R.sub.3 and R.sub.4 are both methyl or ethyl groups.
The amides wherein R.sub.2 is hydrogen or methyl, E is ethyl or propyl and R.sub.3 and R.sub.4 are methyl or ethyl are commercially available but are not as common as (meth)acrylate esters. Canadian Pat. Nos. 595,642 and 583,352 disclose the preparation of some of these amides.
The .alpha.,.beta.-unsaturated amide may also be employed as a cationic or amphoteric salt, e.g., EQU CH.sub.2 .dbd.CR.sub.2 CONHENR.sub.3 R.sub.4 (R.sub.6).sub.y.sup.+ X.sub.z.sup.-y
wherein the substituents are as heretofor defined.
In one embodiment, R.sub.6 is methyl and X is methosulfate and in another embodiment, R.sub.6 is --CH.sub.2 CH.sub.2 CO.sub.2.sup.-.
Cationic and amphoteric derivatives are most usually made, however, by subsequent alkylation of .alpha.,.beta.-unsaturated amide adducts.
Perfluoroalkyl thiols useful herein are well documented in the prior art. For example, thiols of the formula R.sub.f R'--SH have been described in a number of U.S. Patents including U.S. Pat. Nos. 2,894,991; 2,961,470; 2,965,677; 3,088,849; 3,172,190; 3,544,663; and 3,655,732.
Thus, U.S. Pat. No. 3,655,732 discloses mercaptans of formula EQU R.sub.f --R'--SH
where R' is alkylene of 1 to 16 carbon atoms and R.sub.f is perfluoroalkyl and teaches that halides of formula R.sub.f --R'-hal are well known. Reaction R.sub.f I with ethylene under free-radical conditions gives R.sub.f (CH.sub.2 CH.sub.2).sub.a I as is further taught in U.S. Pat. Nos. 3,088,849; 3,145,222; 2,965,659 and 2,972,638.
U.S. Pat. No. 3,655,732 further discloses compounds of formula R.sub.f --R'--X--R"--SH where R' and R" are alkylene of 1 to 16 carbon atoms, with the sum of carbon atoms of R' and R" being no greater than 25; R.sub.f is perfluoroalkyl of 4 through 14 carbon atoms and X is --S-- or --NR'" where R'" is hydrogen or alkyl of 1 through 4 carbon atoms.
U.S. Pat. No. 3,544,663 teaches that the mercaptan EQU R.sub.f CH.sub.2 CH.sub.2 SH
where R.sub.f is perfluoroalkyl of 5 to 13 carbon atoms, can be prepared by reacting the perfluoroalkylalkylene iodide with thiourea or by adding H.sub.2 S to a perfluoroalkyl substituted ethylene (R.sub.f --CH.dbd.CH.sub.2), which in turn can be prepared by dehydrohalogenation of the halide R.sub.f --CH.sub.2 CH.sub.2 --hal.
The reaction of the iodide R.sub.f --R'--I with thiourea followed by hydrolysis to obtain the mercaptan R.sub.f --R'--SH is the preferred synthetic route. The reaction is applicable to both linear and branched chain iodides. U.S. Pat. No. 3,514,487 described perfluoroalkoxyalkyl iodides of general formula EQU (CF.sub.3).sub.2 CFOCF.sub.2 CF.sub.2 (CH.sub.2 CH.sub.2).sub.m I
where m is 1-3.
Particularly preferred herein are the thiols of formula R.sub.f CH.sub.2 CH.sub.2 SH where R.sub.f is perfluoroalkyl of 6 to 12 carbon atoms. These R.sub.f -thiols can be prepared from R.sub.f CH.sub.2 CH.sub.2 I and thiourea in very high yields.
The quaternary ammonium derivatives (cationic and amphoteric salts) of formula II can be prepared from the compounds of formula I by methods well known to the art (e.g., U.S. Pat. No. 2,759,019).
The addition of a perfluoroalkylthiol of formula R.sub.f R.sub.1 SH to an .alpha.,.beta.-unsaturated amide is a base-catalyzed reaction (Hauben-Weyl, Methoden der Organischen Chemie, Vol. 9, pp. 123-6). Since the amino group containing compounds are themselves basic, it is generally not necessary to use a catalyst for the Michael type addition. The addition reaction can be carried out neat or in a solvent employing reaction temperatures ranging from 10.degree. to 150.degree. C and reaction time from minutes to 18 hours. Suitable solvents are such in which the reactants are soluble at reaction temperatures and include aliphatic or aromatic hydrocarbons such as heptane, benzene, toluene, etc.; chlorinated or fluorinated aliphatic or aromatic hydrocarbons such as methylene chloride, chloroform, methyl chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, Freon's such as 1,1,2-trifluoro-1,2,2-trichloroethane, etc., chlorobenzene, benzotrifluoride or hexafluoroxylene, ketones, esters and ethers such as acetone, methyl isobutyl ketone, ethyl acetate and higher homologs, dialkyl ethers, tetrahydrofuran, ethylene glycol monomethyl or monoethyl ether, ethylene glycol dimethyl or diethyl ether, and acetonitrile.
If possible it is preferred to carry out the addition reaction in bulk.
Such fluorochemical surfactants are useful to improve or impart properties such as: wetting, penetration, spreading, leveling, foam stability, flow properties, emulsification, dispersion, and oil and water repellency. Based on these unique properties are numerous applications, some of which follow. Although applications are suggested for a particular use area, the general applicability of each concept is inferred for other applications.